map.TestMoveX
Apply horizontal movement to an object's position and test if it will collide.
Syntax
map.TestMoveX(x, y, w, h, newx)
Parameters
x- Horizontal position of the rectangle.y- Vertical position of the rectangle.w- Width of the rectangle.h- Height of the rectangle.newx- New horizontal position of the rectangle.
Returns
A +/- integer offset that when added to `newx` will remove the object under test from collision. A zero value indicates no collision has occurred.
About
Knowing whether a collision has happened is often not enough,
as you might need to keep the player inside a known region.
map.TestMoveX and map.TestMoveY allow you to test if a
potential horizontal or vertical movement will cause a
collision.
If so, it will return a correction factor needed to remove the object from the collision. In this way, you can build walls that players can slide along and won’t escape from.
Only valid map regions are tested for collisions; positions that are off the map area will always return 0.
The `TestMove-` functions only check for collisions once at the new location. If the distance is large enough, they may miss potential collisions (e.g. halfway
between the old and new locations).